APL Wiki
MildServer - A Simple Web Server for APL
Warning: This page is very much work in progress and probably ends quite abruptly. Hope to have the first revision completed by the end of Sunday December 28th.
The MildServer is an experimental framework for simply developing web applications in APL. The main goals of the MildServer project are:
1. Provide a framework which makes it possible for anyone who can write an APL function to turn it into a web page without having to learn much. 2. Experiment with the use of APL code in Unicode files to run an "Open Source" project.
Although the APL code is intended to be "open source", Dyalog APL Version 12.0. is required as the engine for the MildServer - if you don't have it you should be able to get a free or cheap version from the Dyalog Download Zone. Dyalog v12 is the only component required to host your own web server.
Except for a "bootstrap" workspace, all the code which implements the framework itself and the web applications built upon it are stored in Unicode text files, and the framework is intended to be easy to extend. The project is maintained using SubVersion: If it takes off as an open source project, the idea is to expose this subversion server to contributors.
What IS a Web Server Anyway?
A Web Server is a process running on a machine somewhere, which accepts connections via TCP/IP. Over these connections, the Web Server and its client (typically a "Web Browser") communicate using a protocol called HyperText Transfer Protocol, or HTTP. The incoming HTTP requests typically contain commands to retrieve a "resource". For example, "GET index.htm" would be a command to retrieve the contents of a named page. If the MildServer is working according to its design, you should not need to learn anything about TCP/IP or HTTP - this should all be handled automatically.
HTTP responses generally contain text in a format called HyperText Markup Language - or HTML. You WILL need to learn some basic HTML in order to write Web Applications. Although the MildServer contains functions which will help you generate HTML, you will need to know the basic principles of HTML in order to feel comfortable using them. It is a good idea to spend 20-30 minutes looking at the beginning of one of the many excellent HTML tutorials available on the internet.
Much of the information on the internet is in the form of static web pages: These are simply text files containing text marked up as HTML. When you request one of these pages from a Web Server, it simply transmits the content of the file to the client. The fact that a web page is static doesn't mean that it never changes: Your application could be updating the HTM files every few seconds with the latest information that you want to make available.
However, most Web Servers support some kind of scripting, which means that the page being served up contains embedded code which is executed when the resource is retrieved. This allows you to server up web pages which provide a "user interface", which contains a user interface and changes dynamically in response to input from the user.
(Time to go shopping, back soon)